Analysis Of Plastic Dynamic Response On Steel Beam Subjected To The Explosive Loading

The plastic dynamic response of beam-slab structure subjected to the explosive loading is the foundation of analysis on the structural antiknock dynamic response, and there is important theoretical significance and engineering application value. This paper takes independent steel beam subjected to the explosive loading as the research object, and does research on the plastic stress and deformation response of the steel beam. Main contents are as follows:(1) This paper does research on the dynamic response of simply supported steel beam subjected to the explosive loading using rigid-plastic model. Double exponential explosion overpressure curve is applied on the simply supported steel beam, and the relationship between the maximum deformation of simply supported steel beam and time is analyzed. With the characteristics of the plastic hinge, the relationship between the location of plastic hinge and the motion law of the steel beam is established. Variation rule of deflection, velocity and rotation etc. parameters of the beam over time is obtained, and finally the maximum residual deflection of simply supported steel beam subjected to the explosive loading is obtained.(2) With the characteristics of the moving plastic hinge, the motion law of the beam is divided into four stages. In the first stage, the steel beam is stationary, and there is no plastic hinge generating; In the second stage, one stationary hinge generates in mid-span of the steel beam, through the relationship between the rigid section on both sides and intermediate plastic hinge, the motion law of the steel beam is obtained; In the third stage, two moving plastic hinge generate on the beam, through the relationship between the rigid section on both sides and intermediate plastic section, the motion law of the steel beam is obtained; In the last stage, the two moving plastic hinges are combined into one stationary hinge, and the motion law is similar to the situation of the second stage, and until the beam is stationary, the maximum residual deflection is obtained.(3) With LS-DYNA finite element analysis software, the dynamic response ofâ… -type steel beam subjected to the explosive loading is analyzed. With the simply supported beam and clamped beam as the research object, the stress, strain and deformation of seven key points on the beam is analyzed. The research shows that for the simply supported beam the maximum deformation of the beam is concentrated on the edge of the upper flange and the lower flange of the supports, and the maximum stress is located on the intersection point of the mid-span flange with the web. For the simply supported beam, the stress on the upper flange is higher than the lower flange, and the maximum effective plastic strain appears on the medial axis of the mid-span web. In a word, the local deformation is larger than the global deformation.